It's slightly complicated
For current products (e.g. SampleTank 4, but not SampleTank 3): downloads, installs, registrations and authorizations are handled using the IKPM (the IK Product Manager) program. My understanding is that the downloaded files can be saved somewhere and used later for re-installation and authorization, again using the IKPM.
Fol older products, the installers would be downloaded from your User Area / My Products, then you would run the installer yourself and use the Authorization Manager to authorize them. Again, you can backup the downloaded files and use them again later.
Either way, you should be OK. And, if you run into problems, forum users or Technical Support should be able to sort things out (as long as you do not try to do several things at once
).
A1: Re-install on the
same computer should re-use the same Authorization. If you change the hardware, the authorization process may consider the PC to be a different one and use another authorization. But, you have 10 for each product, and if you ever run out, then Support will, if the circumstances are reasonable, reset them.
A2: The "180 days" only applies to the main Sounds Library downloads. If you needed to download them again after that period, you would need to purchase ONE Download Reactivation Credit to make them all available for another 180 days.
-- so, just keep a back-up somewhere,
-- software downloads are always available,
-- sounds library
updates are separate downloads and are always available.